The present invention relates generally to manufacture of surgical sponges each formed of a fluid absorbing fibrous-web body with a string or thread, preferably containing material opaque to x-ray radiation, attached thereto. More particularly, the present invention is directed to the method and apparatus for automatically fabricating such surgical sponges, especially neurosurgical sponges, in a continuous manner.
Surgical sponges of various shapes and sizes have long been used in a myriad of surgical procedures for the absorption of blood and body fluids, packings and the like. The surgical sponges are frequently saturated with a saline solution or other solution for protecting tissue during the use of suction devices. Recent developments in the preparation of surgical sponges, particularly neurosurgical sponges, included the joining of a relatively long locator string or thread to a surface of the sponge body to facilitate locating and retrieval of the sponges from body cavities. These strings commonly project from the sponge body a distance of about 12 inches and incorporate a material which is opaque to radio waves in the x-ray band to facilitate the locating of the surgical sponges in body cavities.
The fibrous-web forming the body of the sponge is formed of highly absorbent fibrous material, such as rayon, in which the fibers are chemically and/or mechanically bonded into a mat-like construction which is characterized by minimal fiber loss during use. The sponge body can be of any desired thickness, commonly in the range of about 1.0 to about 3.00 millimeters in thickness, which is sufficient for fluid absorption, possesses adequate permeability for use with fluid suction devices, and PG,3 is sufficiently pliable to serve as a tissue wipe. The sponge body has been formed in various configurations including round, oval, square or rectangular. The surgical sponges are available in various sizes are commonly in the range of about 1/4 inch to about 6 inches in length and about 1/4 inch to about 31/2 inches in width.
The locator string joined to the sponge body is preferably formed of a bundle of elongated monofilaments, preferably of a polymeric thermoplastic material such as polypropylene, that have been impregnated with an x-ray opaque material such as barium sulfate. A sufficient number of monofilaments are incorporated in the bundle to assure that the string will be readily detectable during the use of a typical low-power portable x-ray unit as commonly utilized in surgical arenas. The bundle of monofilaments are, in turn, overwrapped with one or more layers of helically wound yarn, preferably fibrous, which serves to bind together the x-ray opaque monofilaments and enhance the tensile strength of the string. The yarn has been satisfactorily formed of medically acceptable materials such as cotton and various polyesters.
The joinder of the string to the sponge body has been achieved by attaching at least an end segment of the string to a surface of the sponge body by employing any suitable bonding technique capable of forming an adequately strong bond between the string and the sponge body. A preferred technique of achieving this joinder between the sponge body and the string is a heat-pressure bond provided by ultrasonic welding. The string is joined to the surface of the sponge over a cross-sectional length thereof which is adequate to assure the presence of a bond of sufficient integrity to remain intact during use of the surgical sponge. In the case of smaller surgical sponges, e.g., neurosurgical sponges, the bond between the string and the sponge body is preferably provided over essentially an entire length dimension of the sponge body. When using ultrasonic welding as the bonding technique, the string components, i.e., both the yarn overwrap and the monofilaments forming the encased bundle, are preferably formed of thermoplastic materials so that they jointly contribute to the formation of the bond with the sponge body.
Further and more specific details pertaining to surgical sponges, including neurosurgical sponges, are set forth in assignee's copending U.S. patent application Ser. No. 07/312,029, filed on Feb. 17, 1989 and entitled "Surgical Sponge." In as much as the present invention pertains to the manufacture of sponges such as described in assignee's copending application, this copending patent application is incorporated herein by reference.
The fabrication or manufacture of surgical sponges of the type described above and in assignee s aforementioned copending U.S. patent application was previously achieved by precutting a selected number of shaped sponge bodies of a particular size and shape from a roll of sponge material. These sponge bodies were then placed one at a time, by hand, over an anvil of an ultrasonic welder. The string was then placed, by hand, over the surface of the sponge body atop of the anvil and properly aligned under the horn of the ultrasonic welder to effect the bond between the string and the underlying sponge body. This "custom" fabrication of each surgical sponge was not only time consuming and expensive but lacked a desired level of repeatability and quality control. For example, the placement of the string over the sponge body required that each string be properly placed on each sponge surface under the horn of the welder and then maintained in this position without bends or wrinkles during the bonding process. This step of the bonding process introduced a quality control problem since it was difficult to properly place the string and maintain it in a proper orientation during welding which is necessary in order to assure that each surgical sponge possessed an adequate level of bonding between the string and the sponge body to be utilized in envisioned surgical procedure. The handling of the sponge body in the course of the prior art fabrication techniques also tended to disrupt the fibers of the body and promote linting during subsequent use of the surgical sponge. The practice of the present invention minimizes handling of the sponge bodies so that the integrity of the sponge web is better maintained.